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FULL SCALE IN-SITU GASEOUS REDUCTION OF HEXAVALENT CHROMIUM IN VADOSE ZONE SOILS WITH H2S GAS
Craig, K. | RemTEC Summit, February 26-28, 2019, Denver, Colorado. 24 slides, 2019

Hydrogen sulfide (H2S) was used to remediate Cr(VI) in vadose zone soils beneath a former plating shop. Although well above groundwater, treatment of the Cr(VI) through standard approaches was infeasible due to the overlying structure or inadvisable due to the potential to mobilize Cr(VI) to groundwater. After direct excavation of the accessible impacted soil in the upper 10 ft, an in situ gas reduction treatment area was established around the limited area with deeper impacts. The H2S injection/extraction system was designed and built to inject an inline stream of H2S gas into a nested injection well at a concentration of ~500 ppm, while simultaneously extracting from a ring of extraction wells to control and treat excess H2S gas. Post-remediation sampling of the soil within the treatment area showed excellent Cr(VI) reduction, leading to a no-further-action determination. https://www.remtecsummit.com/ext/resources/Static-Pages/presentations/Kirk-Craig.pdf



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